Study on the Sediment Discharge Effect of the Swirling Flow in a Desilting Channel with Swirling Flow

The desilting channel with swirling flow is an innovative technology for separating water and sediment in channels based on the strong carrying capacity of swirling flow. The two-phase flow of water and sediment in the desilting channel is simulated using the realizable k–ε model, volume of fluid method, and discrete phase model based on experimental tests to indicate its water–sediment characteristics. The shape factors of sediments with varying particle sizes are determined by comparison to model test results. The effectiveness of sediment discharge in the desilting channel under continuous sediment inflow is examined, and the movement characteristics of sediment within the channel and the sediment transport pipe are analyzed. The results demonstrated that when the shape factors of sediments with different particle sizes range from 0.2 to 1.0, the simulated sediment trapping efficiency for particle sizes of (0.075, 3.000] mm in the desilting channel with swirling flow closely aligns with the experimental values under local inflow conditions from the top of the channel, with a relative error of only 3.5%, primarily attributed to fine sediment particles sized (0.075, 0.160] mm. When sediment is continuously imported from upstream channels at a mass flow rate of 60.0 g/s, the sediment content in the channel rapidly decreases due to the diversion by the swirling flow generator for hyperconcentrated flow at the bottom of the channel. The sediment content at the channel bottom before and after the swirling flow generator is 44.00 and 0.07 kg/m3, respectively. The swirling flow in the sediment transport pipe exhibits a notable sediment-carrying effect, with sediment primarily distributed near the wall of the pipe due to the strong centrifugal action of the swirling flow, where the maximum sediment content reaches approximately 200.00 kg/m3. The sediment trapping efficiency of the desilting channel with swirling flow is 95.98% for particle sizes of (0.075, 3.000] mm under continuous sediment inflow conditions. Only a small amount of fine sediment enters the downstream channel as suspended matter, and there is no significant sediment deposition in the channel and sediment transport pipe, indicating that the desilting channel with swirling flow is an efficient and continuous water–sediment separation technology. These results can provide valuable insights for applying desilting channels with swirling flow in engineering projects and the study of water–sediment characteristics. © 2024 Sichuan University. All rights reserved.